Star power didn't do much to attract moviegoers to the multiplex this weekend, as two celebrity-heavy films were unable to jump-start the box office.

"Pain & Gain," featuring typically reliable box-office draws Dwayne Johnson and Mark Wahlberg, debuted with a $20 million, according to an estimate from distributor Paramount Pictures. Fortunately, the studio only spent $26 million to produce the Michael Bay-directed action comedy — otherwise, its opening would be considered more troublesome.

"The Big Wedding," starring an ensemble cast that includes Robert De Niro, Katherine Heigl and Diane Keaton, was the only other picture to launch this weekend. The movie — which cost nearly $10 million more to make than "Pain & Gain" — collected a disappointing $7.5 million during its opening weekend.

As a result, ticket sales were down 19% compared with the same three-day period last year, while year-to-date receipts and attendance have each tumbled roughly 12%.

Meanwhile, those who turned up to see the weekend's new films didn't like them much. Each movie received an average grade of C+, according to market research firm CinemaScore — spelling bad news for word-of-mouth in weeks to come.

"Pain & Gain," about bodybuilders who go on a crime spree in 1990s Miami, was part of a two-picture deal filmmaker Bay has with Paramount. The director behind the "Transformers" franchise will deliver the second film in that deal — the fourth "Transformers" film, also starring Wahlberg — in June 2014.

Outside of the alien-robot film series, Bay hasn't had much luck at this box office in recent years. His $100-million-plus sci-fi flick "The Island" tanked domestically in 2005, bringing in just $35.8 million in the U.S. and Canada.

"Pain & Gain," which received middling reviews, appealed to a slightly older audience, as 63% of the crowd was over the age of 25. The movie doesn't open overseas until August.

Critics loathed "The Big Wedding," a remake of a 2006 French film about a family brought together as two of its own walk down the aisle. At least distributor Lionsgate doesn't have much of an investment in the movie: The studio contributed less than $10 million to the $35-million budget — the rest of which was paid for by Avi Lerner's Millennium Films.

As expected, the movie appealed heavily to females, who made up 77% of the audience. Heading into the weekend, the studio tried to interest that demographic in the movie by offering a buy-one, get-one-free ticket promotion online.

The only exceptionally positive news at the box office this weekend came from abroad, where "Iron Man 3" got off to a fantastic start in advance of its U.S. opening on Friday. The Marvel Studios production was No. 1 in 42 international countries and collected $195.3 million — more than the $185.1 million "The Avengers" launched with in its opening weekend abroad last summer.

The movie did well in South Korea and Australia this weekend but performed best in the United Kingdom, where it grossed $21.5 million. The film also posted the biggest opening weekend ever in a handful of locations, including Argentina and Hong Kong. The picture starring Robert Downey Jr., which is being distributed by Walt Disney Studios, has yet to open in a few major markets, including Russia and China.

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